1. Field of the Invention
The present invention relates to a printer for a printing paper roll, and more particularly to a printer in which the printing paper roll is easily loaded.
2. Description Related to the Prior Art
Among several kinds of printing paper or recording paper for a printer, there is a printing paper roll (hereafter paper roll), in which a long continuous printing paper is rolled around a roll core. The paper roll is loaded through a paper feed magazine of the printer, or directly into a paper roll chamber of the printer. The paper feed magazine or the paper roll chamber has a pair of frames, on which bearings, for example openings, are formed for supporting the shaft. When the paper roll is loaded, the shaft is fitted in a hole of the roll core to rotatably support the paper roll between the frames. Further, there is also another type of loading for the paper roll, in which paper holders are attached to both ends of the roll core such that the shaft protruding from the paper holders is inserted in the openings of the frames.
However, in the apparatus described above, the shaft has to be inserted in the bearings after the shaft is inserted in or the paper holder is attached to the roll core. Accordingly, it is hard to load the paper roll. Further, the radius of the paper roll may be reduced if it has been already used. Namely, the paper roll of a smaller radius is often loaded in the printer. Thereby, the chucking of the paper roll in the printer is troublesome.
A main object of the present invention is to provide a printer for a printing paper roll which can be easily loaded.
Another object of the present invention is to provide a printer for the printing paper roll in which the chucking of the printing paper roll in the printer is always carried out even if the radius of the printing paper roll is different.
In order to achieve the above and other objects, a printer for a printing paper roll of the present invention includes an openable loading lid, and a holder plate attached to the loading lid. An open angle between the loading lid and the holder plate is determined in accordance with a radius of the printing paper roll. A position of the printing paper roll relative to the loading lid is determined in accordance with the open angle.
A positioning device has first and second link mechanisms attached to the loading lid and the holder plate. The first and second link mechanisms include first and second positioning plates to contact to a periphery of the printing paper roll. After the printing paper roll is put on the loading lid, the loading lid is closed. Thereby the loading lid relatively moves to the holder plate, and the open angle becomes smaller. When the periphery of the printing paper roll contacts to the first and second positioning plates and the holder plate, the open angle decreases no more. Then, the loading lid and the holder plate move together with the certain open angle while the printing paper roll is held between them. The loading lid and the holder plate are rotatable, and preferably provided on a same shaft.
When the loading lid is set at a closed position, a detector generates a detection signals. Beside on the detection signal, a roll supporting device is driven. The roll supporting device slides a first or second support shaft to chuck and rotatably support the printing paper roll at a predetermined position.
According to the invention, the chucking of the printing paper roll is carried out when the loading lid is closed after putting the printing paper roll on it. Further, the loading lid is perfectly closed, a shaft hole of the printing paper roll is at a predetermined position, independent of changing of the radius of the printing paper roll. Therefore, the printing paper rolls having different radiuses can be surely chucked.